Rotary touch scanner

ABSTRACT

A rotary touch scanner for reading a bar code pattern includes: an outer frame formed with an opening portion, a rotary ring rotatably housed in the outer frame, a plurality of convex lenses mounted on an outer periphery of the rotary ring at regular angular intervals, rotary ring rotating device associated with the rotary ring, and a light receiving element disposed at a center of the rotary ring and having a light receiving surface directed to the opening portion of the outer frame; light scattered from a bar code label disposed in front of the opening portion of the outer frame being condensed and further focused onto the light receiving surface of the light receiving element as a real image through one of the convex lenses rotated by the rotary ring rotating device, continuously.

This is a continuation of application Ser. No. 08/507,994, filed Jul.27, 1995 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotary touch scanner, and morespecifically to a rotary touch scanner suitable for use as a bar codepattern reader.

2. Description of the Prior Art

FIG. 1 shows an example of a prior art touch scanner. In FIG. 1, thetouch scanner is composed of an image sensor (e.g., CCD (charge coupleddevice)) 21, a convex lens 22, a red light emitting device 23, etc.Further, the reference numeral 24 denotes a bar code label. In FIG. 1,the bar code label 24 is irradiated with red light emitted by the redlight emitting device 23. The light reflected from the bar code label 24is condensed and further focused through the convex lens 22 onto thefront surface of the image sensor 21 as a real image thereof. On theother hand, the CCD image sensor 21 is driven to scan the real image ofthe bar code label pattern focused thereon, to read the bar codepattern.

In the prior art touch scanner as described above, since the bar codelabel pattern can be read momentarily, as far as the touch scanner isbrought into soft contact with the bar code label, the usability thereofis excellent, as compared with a pen scanner by which a bar code labelpattern is scanned manually so as to cross the bars.

In the above-mentioned prior art touch scanner, however, there existsuch problems in that the light irradiated upon the label is limited toonly red light (monochromatic light); the resolution (resolving power)is not sufficient and further difficult to increase it, in spite of thefact that the label has been recently printed by a high density printer;the costs of the parts assembled in the scanner are relatively high,etc.

In more detail, first since the red light is used as the irradiationlight, it is impossible to read the bar code label patterns printed byred-based colors. In addition, the bar code label pattern can be readonly under some illumination conditions such that the touch scanner canbe used only below the illumination intensity of 3000 lux (byfluorescent light). Further, it is of course impossible to read bar codepatterns on a picture displayed on a Braun tube (cathode-ray tube) or aliquid crystal display.

Secondly, the resolution is not high due to the aberration of the convexlens, the non-uniformity of the sensing characteristics of the CCDelements, etc., even if the illumination light is uniform. In the caseof the prior art touch scanner, since the monochromatic light is used,although the chromatic aberration can be eliminated, the sphericalaberration will not be eliminated. Further, although the resolution canbe increased when the size of the CCD elements is reduced, it isdifficult to keep an excellent uniformity of the sensing characteristicsof the CCD elements. Further, when the lens aperture is reduced,although the resolution can be somewhat improved, the illumination lightof more uniform and higher intensity is required to that extent.

Thirdly, the reason why the parts cost is high in the prior art touchscanner is that: an optical system for reading two-dimensional image isprovided, in spite of the fact that only one-dimensional bar codepattern image is required to read. In addition, a scanning systemcomposed of the CCD image sensor of high resolution and an electroniccircuit for driving and controlling the CCD image sensor is necessary.

SUMMARY OF THE INVENTION

With these problems in mind, therefore, it is the object of the presentinvention to provide a touch scanner usable under white light, high inresolution, deep in depth of field, less in chromatic and sphericalaberrations, low in parts and manufacturing cost, easy to handle, etc.

To achieve the above-mentioned object, the present invention provides arotary touch scanner for reading a bar code pattern, comprising: anouter frame 5 formed with an opening portion 2; a rotary ring 3rotatably housed in said outer frame; a plurality of convex lenses 4mounted on an outer periphery of said rotary ring at regular angularintervals; rotary ring rotating means 6, 7, 8 associated with saidrotary ring; and a light receiving element 1 disposed at a center ofsaid rotary ring and having a light receiving surface directed to theopening portion of said outer frame, light scattered from a bar codelabel disposed in front of the opening portion of said outer frame beingcondensed and further focused onto the light receiving surface of saidlight receiving element as a real image through one of said convexlenses rotated by said rotary ring rotating means, continuously.

Further, it is preferable that the rotary touch scanner furthercomprises a correction lens 12 fixed to said outer frame and disposed infront of said light receiving surface of said light receiving element 1for correction of difference in distance between the bar code label andsaid light receiving element caused by change in read angle θ of saidlight receiving element.

Further, it is preferable that a plurality of sets of said lightreceiving elements and said convex lenses are stacked at multistage inan axial direction of said rotary ring, to read a multistage bar codelabel patterns, simultaneously.

Here, it is preferable that said rotary ring rotating means comprises: amotor 6 having a motor shaft 7; a worm 8 attached to and end of themotor shaft; and a worm gear 9 formed on the outermost periphery of saidrotary ring in mesh with said worm.

In the rotary touch scanner according to the present invention, since anovel scanning method such that the convex lenses mounted on the rotaryring are rotated to scan bar code label pattern continuously, it ispossible to use only the paraxial rays incident upon near the opticalaxis of the lenses, so that it is possible to realize a touch scannerless in chromatic and spherical aberrations, high in resolution, and lowin cost.

In more detail, when the convex lenses mounted on the rotary ring arerotated, light scattered from an intersection (A1 or A2 point) betweenan extension line of the optical axis of the convex lens and the barcode label is condensed and further focused onto the same surface (Bpoint) of the light receiving element (located at the central point ofthe rotary ring) continuously through the convex lenses to obtaincontinuous real label pattern images. Here, the essential point of thescanning method according to the present invention is that the center ofthe light receiving element (B point) and the bar code label (A1 or A2point) are both always kept on the optical axis of one of the convexlenses at all the time when the rotary ring is being rotated to sensethe bar code label pattern.

In the above-mentioned optical system, since a real image can be focusedonto the light receiving element on the basis of only the paraxial rays,it is possible to obtain a real image of high resolution, whileminimizing the influence of the chromatic and spherical aberrations uponthe image to be sensed.

Further, since the correction lens fixed to the outer frame is disposedin front of the light receiving surface of the light receiving element,it is possible to further correct the difference in distance between thesensed bar code label and the light receiving element caused by thechange of the read angle or the elevation angle θ of the light receivingelement.

Further, when one set of the light receiving element and the convexlenses are stacked at multistage in the axial direction of the rotaryring, it is possible to read the multistage bar code label patterns atthe same time by a single touch scanning operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from the followingdetailed description of a preferred embodiment of the invention, takenin conjunction with the accompanying drawings, in which like referencenumerals refer to like parts, and in which:

FIG. 1 is a cross-sectional view showing an example of the prior arttouch scanner;

FIG. 2A is a longitudinal cross-sectional view showing a firstembodiment of the rotary touch scanner according to the presentinvention;

FIG. 2B is an enlarged cross-sectional view showing the convex lensdriving portion of the first embodiment shown in FIG. 2A;

FIG. 3A is a longitudinal cross-sectional view showing a secondembodiment of the rotary touch scanner according to the presentinvention;

FIG. 3B is an enlarged cross-sectional view showing the convex lensdriving portion of the second embodiment shown in FIG. 3A; and

FIG. 4 is an enlarged cross-sectional view showing the convex lensdriving portion of the third embodiment of the rotary touch scanneraccording to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described in detailhereinbelow with reference to the attached drawings.

FIGS. 2A and 2B show a first embodiment thereof. The rotary touchscanner comprises an outer frame or enclosure 5; a rotary members orring 3; a light receiving element 1; a plurality of convex lenses 4;lens rotating means composed of a motor 6, a motor shaft 7, a worm 8 anda worm gear 9, and a battery 11.

The rotary member or ring 3 is rotatable about a rotation axis or axle3A which extends through a first point B on enclosure or frame 5. Eachof the convex lenses 4 has a center defining a second point fixed to therotary member or ring 3. Both the first point and the second pointreside on an imaginary plane extending perpendicular to the rotationaxis 3A, as best illustrated in FIG. 2A. The enclosure or frame 5 has anopening 2 which has a periphery which crosses the imaginary plane at apair of additional points which cooperate with the first point B todefine an angular sight zone θ_(MAX). The angular sight zone covers anordered total of bar codes between points A1 and A2 in an array of barcodes when an object carrying the array of bar codes is broughtsubstantially into contact with the opening in the enclosure, asillustrated schematically at the left-hand side of FIG. 2A.

The light scattered from a bar code label is introduced through theopening portion 2 of the outer frame 5 and then condensed through anyone of the convex lenses 4 arranged on the outer peripheral of therotary ring 3 at regular angular intervals. Therefore, a real image of abar code label pattern can be focused onto the light receiving surfaceof the light receiving element 1 arranged at the center of the rotaryring 3. Here, the focal distance of each of the convex lenses 4 is ofcourse so designed that a real bar code pattern image can be justfocused to a center of the rotary ring 3.

In use, when the motor 6 is started by power of the battery 11, forinstance, since power is transmitted from the motor 6 to the rotary ring3 by way of the motor shaft 7, the worm 8 fixed to an end of the motorshaft 7, and a worm gear 9 formed on the outer circumference of therotary ring 3, the rotary ring 3 is rotated about its center axle 3Adisposed at the lower portion of the rotary ring 3 supported by a needlebearing 10 (as shown in FIG. 2B). Accordingly, the three convex lenses 4can scan the surface of the bar code label pattern continuously, so thata real image of the bar code pattern can be focused on the lightreceiving element 1 continuously.

Here, in this embodiment, when the light receiving surface of the lightreceiving element 1 is rectangular in shape (the lateral width W (shownin FIG. 2B) is 0.05 mm) and when the magnification of the real image toa subject (bar code patterns) to be sensed is 0.5, the resolution(resolving power) is 0.1 mm. In this connection, the resolution of theprior art high-resolution scanner is 0.15 mm or more.

As described above; in the light receiving element 1 of the presentinvention, since the lateral width W (=0.05 mm) of the light receivingsurface is very narrow, the received light is limited to only theparaxial rays, so that it is possible to obtain a real image ofextremely small chromatic and spherical aberrations. In addition, sinceonly the paraxial rays are sensed, the aperture diameter of the convexlenses 4 can be reduced sufficiently, so that it is possible to increasethe depth of field. In FIG. 2A, when the focal distance f of the convexlens 4 is determined 20 mm and the aperture diameter A of the convexlens 4 is determined 2 mm, the F-value (f/A=20/2) is about 10, so thatit is possible to obtain a sufficiently large depth of field. In thisconnection, in the case of the prior art scanner, the depth of field is±5 mm from the bar code label read position when a label of 13 positionsprescribed by JAN is read. Here, JAN implies Japanese Article Numbersindicative of commodity bar code numbers prescribed by JapaneseIndustrial Standard.

Further, the read elevation angle θ roughly changes within a range of(30/90)≧tan θ≧-(30/90). Here, 30 mm indicates a half (L3) of thelongitudinal length (2×L3) of the opening portion 2 of the outer frame 5(in FIG. 2A), and 90 mm indicates a length (L1) between an end of theopening portion 2 of the outer frame 5 and the central position B of thelight receiving element 1 (in FIG. 2A). Accordingly, the horizontaldistance between the central position B of the light receiving element 1and the bar code label A1 is about L1=90 mm (at the minimum) at θ=0 andthe oblique distance between the two is about L2=95 mm (at the maximum)at θ=θmax, so that the difference between the minimum and maximumdistances (L2-L1) is approximately (95-90=5 mm). Here, since the depthof field of ±5 mm is allowed relative the bar code label read positionin the prior art scanner, as already explained above, and further sincethe depth of field can be further increased in the present invention,the above-mentioned difference of 5 mm can be considered to lie withinthe allowable range.

Further, in the example shown in FIG. 2A, three convex lenses 4 arearranged at 120° angular intervals. Therefore, whenever the rotary ring3 rotates once, three bar code patterns can be read continuously.Without being limited only to three, when four lenses 4 are arranged at90° angular intervals, it is possible to read four bar code patternscontinuously for each revolution of the rotary ring 3.

Further, although it is preferable to attach an auxiliary lamp(illumination light) near the opening portion 2 of the outer frame 5,where the job or work site is sufficiently bright and thereby asufficient light intensity can be obtained by only the ambient light, itis possible to read bar code patter by covering a part of the aperture 2of the outer frame 5 with a transparent plastic cover (not shown)(without use of any auxiliary illumination light).

Further, the bar code pattern scanned and read by the light receivingelement 1 is further transmitted to another processing unit to decodethe sensed bar code pattern, that is, to detect various data representedby the bar code pattern.

FIGS. 3A and 3B show a second embodiment of the present invention. Inthe first embodiment shown in FIGS. 2A and 2B, there exists a differenceof 5 (=95-90) mm between at the minimum elevation angle (θ=0)) and atthe maximum elevation angle (θ=θ max) of the rotating convex lenses 4 indistance between the light receiving element 1 and the bar code label tobe read. In this second embodiment, a correction lens 12 is disposed infront of the light receiving surface of the light receiving element 1 sothat the above-mentioned difference in distance can be corrected. Inmore detail, the correction lens 12 is fixed to the outer frame 5 by useof an appropriate bracket 12A. Therefore, in this embodiment, it ispossible to always focus a real image of the bar code label pattern ontothe light receiving element 1 more accurately, irrespective of thevariation of the read angle (elevation angle) θ of the rotating convexlenses 4.

FIG. 4 shows a third embodiment of the present invention. In thisembodiment, two sets of the light receiving elements 1 and two sets of aplurality of convex lenses 4 are stacked along the axial direction ofthe rotary ring 3, so that two-stage JANs (bar code labels used forapparel commodities) can be read by only a single touch. That is, theupper stage bar code pattern can be read by the upper lens 4U and theupper light receiving element 1U, and the lower stage bar code patterncan be read by the lower lens 4L and the lower light receiving element1L, respectively at the same time by only a single touch with the barcode label of the two-stage JANS.

In the above-mentioned rotary touch scanner according to the presentinvention, since a novel scanning method is adopted such that aplurality of convex lenses mounted on the rotary ring are rotated, it ispossible to obtain a real image on the light receiving element on thebasis of only the paraxial rays, thus providing various followingfeatures:

(1) Reading under white light

Since only the paraxial rays are used for reading the bar code labelpattern, the reduction of resolution due to chromatic aberration can beminimized. Therefore, it is unnecessary to use monochromatic (red)light, so that any bar code patterns printed by red-based colors can beread. Of course, the bar code patterns can be read under the naturallight and white light. In addition, bar code patterns displayed on aBraun tube (CRT) or a LCD (liquid crystal display) can be also scannedor read.

(2) High resolution

Since only the paraxial rays are used to read bar code patterns, theresolution is not reduced due to spherical aberration. This is becausewhen the rotary ring 3 is being rotated, an intersection point A1 or A2(shown in FIG. 2A) (between an extension line of the optical axis of theconvex lens 4 and the bar code label) and the light receiving elementpoint B (shown in FIG. 2A) are both always located on the same opticalaxis of the convex lens 4. In the prior art scanner, since theperipheral rays incident upon and passed through the outer circumferenceof the lens are detected, the resolution has been reduced due to thespherical aberration.

In lens-rotation scanning method of the present invention, however, theresolution can be increased by simply reducing the aperture width of thelight receiving element 1. On the other hand, in the case of the priorart scanner, since the size of the CCD sensor must be reduced in orderto increase the resolution, there exists a limit of reduction of thesize of the CCD sensor and further a higher technology is required.

(3) Low cost

Since a simple convex lens or a plastic lens can be used, the cost ofthe lenses is extremely low. In addition, since the aberration cannot betaken into account, it is not necessary to use an expensive lens sodesigned as to remove various aberrations.

Further, since a pin-point type light receiving element can be used,without use of any high costly CCD sensor and an electronic circuit fordriving and controlling the CCD sensor, the cost of the light receivingelement can be reduced extremely.

Further, since the structures of the optical system and the electroniccircuit system can be both simplified, the power consumption can besaved markedly. Although the rotary rings 3 must be rotated by the motor6, it is possible to use a motor of low cost and low power consumption,with the result that a small battery can be used as the power of therotary touch scanner according to the present invention.

As described above, in the rotary touch scanner according to the presentinvention, since the lenses mounted on a rotary ring are rotated to scanthe bar code label pattern, it is possible to provide a touch scannersimple in structure, high in resolution, deep in depth of field, usableunder white light, and low in manufacturing cost. The bar code labelshave now being widely used in various physical distribution fields sucha POS (point of sales) or FA (factorial automation), and further even inthe field of OA (official automation). Therefore, the bar code readersof touch scanner type will be widely used in various fields in thefuture in various countries. Recently, some bar codes representative ofChinese characters have been developed, in addition to the bar codesrepresentative of numerical values. As a result, bar code labels will beused more widely all over the world. Therefore, the touch scanner usableunder white light, high in resolution, and low in cost will be requiredmore and more.

Although some preferred embodiments of the invention have been describedabove by way of example only, it will be understood by those skilled inthe field that modifications may be made to the disclosed embodimentswithout departing from the scope of the invention, which is defined bythe appended claims.

I claim:
 1. A rotary touch scanner for reading a bar code patterncomposed of an array of parallel bar codes having arbitrary lengths ofwhich a respective one represents a single code and of which an orderedtotal carries decodable information, the rotary touch scannercomprising:an enclosure having a first point; a rotary member rotatablymounted in said enclosure for rotation about a rotation axis extendingthrough said first point, the rotary member having a second point fixedto the rotary member, both the first point and the second point residingon an imaginary plane extending perpendicular to the rotation axis; theenclosure having an opening having a periphery crossing the imaginaryplane at a pair of additional points cooperating with the first point todefine an angular sight zone covering an ordered total of bar codes inan array of bar codes when an object carrying the array of bar codes isbrought substantially into contact with the enclosure; a light receivingelement positioned at said first point; a convex lens arranged at saidsecond point on said rotary member for focusing light rays incident tosaid opening on said light receiving element when the second point liesin the angular sight zone; a drive means for driving the rotary memberwhereby the second point traverses the angular sight zone repeatedly sothat an image of said ordered total of bar codes is continuously scannedby the light receiving element; and the light receiving element having alight sensing region thereof of predetermined size for receiving firstlight rays of the focused light rays substantially paraxial with respectto the convex lens, and for excluding second light rays of the focusedlight rays surrounding said first light rays, whereby only light raysparaxial with respect to said lens are received by said light receivingelement.
 2. The rotary touch scanner as claimed in claim 1, furthercomprising an additional convex lens located at a third point on saidrotary member spaced from said second point, said third point beingpositioned to traverse the angular sight zone as said rotary member isrotated, for focusing light rays incident to said opening on said lightreceiving element.
 3. The rotary touch scanner as claimed in claim 2,wherein said third point is located at an angular spacing from saidsecond point which is larger than a sight angle of said angular sightzone.
 4. The rotary touch scanner as claimed in claim 3, wherein thedrive means comprises means for driving said rotary member so that saidsecond and third points revolve about said rotation axis atsubstantially constant angular speed.
 5. The scanner as claimed in claim1 wherein said light sensing region is rectangular and has a width of0.05 mm.
 6. A rotary touch scanner for reading a bar code patterncomposed of an array of parallel bar codes having arbitrary lengths ofwhich a respective one represents a single code and of which an orderedtotal carries decodable information, said rotary touch scannercomprising:an enclosure formed with an opening defining an angular sightzone (2×θ_(MAX)) about a scan point in the enclosure, the opening havinga width for scanning an ordered total of parallel bar codes broughtclose thereto; a rotary member rotatable about the scan point; a convexlens arranged on the rotary member so that an optical axis of the lensturns about the scan point, traversing a sight zone, as the rotarymember is rotated; and an image sensing element placed in a vicinity ofthe scan point and comprising sensing means for receiving substantiallyonly light rays incident to the opening, focused by the convex lens andparaxial to the optical axis.
 7. A rotary touch scanner according toclaim 6, further comprising drive means for driving the rotary member torotate.
 8. A rotary touch scanner according to claim 7, wherein thedrive means is accommodated in the enclosure.
 9. A rotary touch scanneraccording to claim 6, wherein the rotary member is enclosed by theenclosure.